Remove

Remove[s1,s2,…] removes the symbols si completely, so that their names are no longer recognized by the Wolfram Language.

Remove[patt1,patt2,…] removes all symbols whose names textually match any of the arbitrary string patterns patti.

Remove[{spec1,spec2,…}] removes any symbols that are equal to or whose names match any of the speci.

Please visit the official Wolfram Language Reference for more details and examples on core symbols.